1. Field of the Invention
This invention relates generally to apparatus for handling chemical and biological substances, and more particularly to automatic pipetting machines.
2. Description of the Related Art
Automatic pipetting machines are used in the chemical and biological fields to automatically pipette fluids from one place to another. To avoid contamination, many automatic pipetting machines use disposable pipette tips which are used once and then thrown away.
Commercially available automatic pipetting machines use several techniques for picking up and discarding disposable pipette tips. For example, several companies use custom molded pipette tips which are specifically designed for insertion and removal from their automatic pipetting machines. Other companies provide automatic pipetting machines which pick-up generic pipette tips with mandrels having "O" rings or hard, plastic plugs as sealing members.
While custom molded pipette tips work fairly well with the machines for which they were designed, they tend to be more expensive than generic pipette tips. On the other hand, automatic pipetting machines which use generic pipette tips experience problems including improper internal sealing, high insertion and removal forces, improper axial alignment, and unpredictable pipette tip heights.